From: boris petkovic
Date: Fri, 22 Dec 2000 04:55:27 -0800 (PST)
Subject: Re: [TSSP] Coils at high elevation
> > > > As fn resonant frequency increases situations > change > > > > -the effect of Cint influence to higher > harmonic > > > > frequency cannot be neglected anymore. > > > > > This year I sent Malcolm an outline of my > papers > > > > where I explained how and why that appears. > > > > > Me: > > > I'd like to see those. > > Boris: > > In these papers ,among other things was shown > that > > influence of Cintrisic could be so dramatic that > > something like very high, say 13th or 15th, > resonant > > frequency for usual no hat helical resonators > actually > > didn't exist. > > In other words,capacitive network of winding acts > on > > incoming waves so dramaticaly that degenerates > > formation of standing waves' notches and nodes. > > After critical high frequency passed,voltage > profile > > over winding could be just a sort of hyperbolic > > function and nothing more ,appearing and > dissapering > > in phase with driving source voltage function. > > Interesting. I've seen the higher resonances peter > out to nothing and assumed it was just an effect of > declining Q at higher frequencies. ---- No,no ..you are wrong about this. --- I've not trusted > the simulator beyond about the 10th overtone due to > it's limited spatial resolution of the physical Cext > and Cint. Last night I explored up to 65th overtone > using tsim, and the equal spacing between overtones > apparent between say 4th and 15th overtones alters > above about the 15th, the intervals gradually > becoming > larger and larger. This is on a very high Q coil. I > assume > this is an artifact of the simulator, but it sounds > like > I need to add exploration of this by measurement to > the > list of things to do! > > Boris, thanks for raising the point. What you are > saying > about Cint is making some sense to me. Perhaps we > can think > of Cint as bypassing and short-circuiting the > inductance at > higher frequencies. Clearly there is knowledge > waiting to > be gleaned from exploration of the higher overtones. > > I'll bet there is a formula to be found for a > cut-off > frequency. Wish I new how to work out a phase > constant, > either an average value for the coil, or as a > function > of position. > To Malcolm (if you read this), Will you be so kind and send to Paul my handwritten papers relating this stuff (aproximately 10 pages)? It would be a real headache for me to write that summary again. Thanks, Boris __________________________________________________ Do You Yahoo!? Yahoo! Shopping - Thousands of Stores. Millions of Products. http://shopping.yahoo.com/
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.